1. Field of the Invention
The present invention relates to a mirror image method for use in an industrial robot, and more particularly, to a method for preparing a mirror image program for mirror image drive.
2. Description of the Background Art
In an industrial robot, it is conventionally known to utilize a mirror image function of the robot so as to determine mirror image points of teaching points associated with one side of a work object. The determined mirror image points are used as teaching points associated with the other side of the work object. Operations, at opposite sides of the work object are carried out on the basis of the aforementioned two kinds of teaching points in a symmetrical manner with respect to a plane passing through an axis of the work object. As shown in FIG. 3, it is also known to symmetrically dispose, with respect to a work object 53 on a working line 52, a first robot 50 responsive to a teaching program, and a second robot 51 responsive to a program containing therein, as teaching points, mirror image points of teaching points contained in the teaching program. The robots 50 and 51 simultaneously carry out operations, symmetrical with each other with respect to the work object 53, at opposite sides of the work object 53.
Conventionally, in a robot of the above-mentioned type, a mirror image 54' of the position of a tool tip point 54 and a mirror image 55' of the position and attitude of a tool mounting center 55 are determined with respect to a mirror plane 56, as shown by way of example in FIG. 4. Then a program according to mirror images is prepared on the basis of these mirror images 54', 55' and a teaching program. In this respect, the conventional art entails drawbacks, e.g., the attitude of the mirror image T' is unsymmetrical with that of the tool T with respect to the mirror plane 56, as shown in FIG. 4.